A dispenser closure widely used in Australia and other countries is described in Australian Pat. No. 446218. Whilst generally satisfactory in use it has been known to leak particularly when a container to which it is fitted is subjected to sudden shocks or a number of containers are stacked one above the other. This particular dispenser closure suffers from the inherent disadvantage that the effectiveness of the seal is dependent on the diaphragmatic transverse wall closure making sealing contact with a peripheral edge of the discharge spout which sealing contact can be broken by increasing pressure within the container.
A dispenser closure which is substantially free of the above mentioned disadvantages is described in Australian Pat. No. 474900. It has been found that in use such a dispenser is hard to operate particularly when the container has been stored in a refrigerator and the rate of discharge is not satisfactory.
Another problem of the dispenser closure of the type described in Australian Pat. No. 474900 is that when the closure is placed in what is known as the dust cap position the internal sealing flange may take a set which interferes with the sealing action after the container has been filled and the closure pushed into the full sealing position.